Independent verification of the saturation hydrogen uptake in MOF-177 and establishment of a benchmark for hydrogen adsorption in metal–organic frameworks

Abstract

Hydrogen isotherms for MOF-177, Zn₄O(1,3,5-benzenetribenzoate)₂, crystals were independently measured by volumetric and gravimetric methods at 77 K to confirm its hydrogen uptake capacity and to establish the importance of calibrating gas adsorption instrumentation prior to evaluating H₂ storage capacities. Reproducibility of hydrogen adsorption experiments is important because non-systematic errors in measurements can easily occur leading to erroneous reports of capacities. The surface excess weight percentage of hydrogen uptake in MOF-177 samples is 7.5 wt% at 70 bar, which corresponds to an absolute adsorbed amount of 11 wt%. These values are in agreement with our previous report and with those found independently by Southwest Research Institute. Considering its well-known structure and its significant H₂ uptake properties, we believe MOF-177 is an excellent material to serve as a benchmark adsorber.